In Fiber-To-The-Premises (FTTP) networks, software or hardware upgrades to or maintenance of Optical Network Terminals (ONTs) and Optical Line Terminals (OLTs) may cause brief interruptions in communications between the ONTs and OLTs. For example, in a software upgrade to the ONT, the ONT loses communication with the OLT during a reboot process used to initialize the ONT with the software upgrade. In some systems, these interruptions in communications, in turn, cause Plain Old Telephone System (POTS) lines of the ONTs to deactivate. An alarm system, such as a burglar alarm system, connected to the ONT via a POTS line may generate an alarm in response to detecting a deactivated POTS line.